The present invention relates to a hermetically circulating, absorption type refrigerator and more particularly, to a hermetically circulating, absorption type refrigerator (hereinafter simply referred to as a refrigerator) having an excellent anti-corrosive effect and a high reliability.
In such a refrigerator, since an aqueous concentrated lithium bromide solution having a high corrosive effect is used as an absorbing solution, a problem of corrosion acting on structural components thereof is raised. To cope with this, a conventional method in which various inhibitors (anti-corrosive agents) are contained in an absorbing solution has been carried out. To enhance an efficiency of the refrigerator, the operational temperature thereof has, recently, been elevated, and it will exceed a temperature of 200.degree. C. in near future. Accordingly, an environment of corrosion becomes considerably severe, and it is difficult to suppress the corrosion with the conventionally used inhibitors.
On the other hand, in an ordinary small size boiler having a simple construction, there is an example in which an electric anti-corrosion method is used. However, since the refrigerator has a complicated inner structure and is formed of various kinds of metal materials such as carbon steel, copper, cupronickel, brass and the like, it is difficult to set anti-corrosive potentials. For this or other reasons, there have been no studies at all as to a corrosion suppression solely or independently in accordance with the electric anti-corrosion method. Also, any attempt has not been made to use simultaneously the effects of the inhibitors and the electric anti-corrosion method for the following reasons.
(1) In the case of using the two effects, the inhibitor is, in general, an inorganic material of oxidizer type, which forms a dense film comprised mainly of Fe.sub.3 O.sub.4 to thereby suppress corrosion. Since an electric resistance of the iron oxide is much higher than that of iron, to make a anti-corrosive current, which is required for the electric anti-corrosion, flow through the film, a voltage higher than usual must be applied between electrodes and structural components of the refrigerator. However, the iron oxide film is continuously and repeatedly subjected to a destruction and a reproduction or repair with the inhibitor, during operation of the refrigerator. When the iron oxide film is destroyed, a current corresponding to a higher voltage is concentrated thereon, as a result of which the destroyed portion is excessively anti-corrosive to generate a hydrogen gas in accordance with a conventional cathode anti-corrosion method. The interior of the refrigerator is kept in a hermetical and vacuum system. Therefore, generation and accumulation of the hydrogen gas cause an elevation of an inner pressure, resulting in remarkable reduction in ability of the refrigerator.
(2) Furthermore, in case that the excessive anti-corrosion state is caused as described above, a pH value of the absorbing solution will be varied in accordance with the effect of OH.sup.- ion generated at the anode as the hydrogen gas is generated.